Chain Extension Reaction Research Articles

Fast Upcycling of Poly(ethylene terephthalate) into Catalyst-Free Vitrimers

We reported a catalyst-free technique to fabricate transesterification-based poly(ethylene terephthalate) (PET) vitrimers via melt reacting PET with N,N′-tetraglycidyldiaminodiphenyl methane (TGDDM) in several minutes. We investigated the effect of TGDDM content on the reaction mechanism and chemical structure of the final products in detail. At low TGDDM content (≤0.5 wt %), branched thermoplastic PET was obtained by the chain-extension reaction between carboxyl groups of PET and epoxy groups of TGDDM. At medium TGDDM content (0.7–1.0 wt %), PET vitrimers with relatively low cross-link density were achieved through the cross-linking reaction between original carboxyl plus hydroxyl groups of PET and epoxy groups of TGDDM. At high TGDDM content (1.2–2.0 wt %), soluble chain-extended products were first formed through reacting original carboxyl and hydroxyl groups of PET with part of epoxy groups of TGDDM, and PET vitrimers were then obtained after the excess epoxy groups were consumed by the newly formed functional groups, which were generated by thermal decomposition of ester groups of PET under catalyzation of tertiary amines of TGDDM moieties. The cross-linked network structure endowed the PET vitrimers with enhanced heat resistance and creep resistance. The obtained PET vitrimers could relax stress rapidly and showed excellent processability and weldability, owing to the fast transesterification between hydroxyl and ester groups under catalyzation of internal tertiary amines. We believe that the facile fabrication technique showed great potentiality for upcycling of PET into vitrimers in large-scale production.

Programming Orientation in Liquid Crystalline Elastomers Prepared with Intra-Mesogenic Supramolecular Bonds.

The large, directional stimuli-response of aligned liquid crystalline elastomers (LCEs) could enable functional utility in robotics, medicine, consumer goods, and photonics. The alignment of LCEs has historically been realized via mechanical alignment of a two-stage reaction. Recent reports widely utilize chain extension reactions of liquid crystal monomers (LCM) to form LCEs that are subject to either surface-enforced or mechanical alignment. Here, we prepare LCEs that contain intra-mesogenic supramolecular bonds synthesized via direct free-radical chain transfer photopolymerization processible by a distinctive mechanical alignment mechanism. The LCEs were prepared by the polymerization of a benzoic acid monomer (11OBA), which dimerized to form a liquid crystal monomer, with a diacrylate LCM (C6M). The incorporation of the intra-mesogenic hydrogen bonds increases the achievable nematic order from mechanical programming. Accordingly, LCEs prepared with larger 11OBA concentration exhibit higher magnitude thermomechanical strain values when compared to a LCE containing only covalent bonds. These LCEs can be reprogrammed with heat to return the aligned film to the polydomain state. The LCE can then be subsequently programmed to orient in a different direction. The facile preparation of (re)programmable LCEs with supramolecular bonds opens new avenues for the implementation of these materials as shape deployable elements.

Preparation of SiO2-g-PMMA hybrid materials employing different photocatalysts of metal-free ATRP and its application for oil-water separation

SiO2-g-PMMA hybrid materials was prepared by grafting the PMMA polymer chains from nano-SiO2 particles surface via metal-free atom transfer radical polymerization (metal-free ATRP). The FT-IR, XPS, SEM, BET and TGA tests proved that PMMA polymer chains was successfully grafted from the surface of nano-SiO2 particles. We discussed the catalytic effect and mechanism of four types photocatalysts in the preparation of SiO2-g-PMMA hybrid materials and chose Rhodamine B catalyst with reduction quenching to prepare SiO2-g-PMMA because its catalytic system has the highest conversion rate under the similar controllable degree. In addition, the kinetic analysis and chain extension reaction of the polymerization process were carried out, and it was found that the concentration of free radicals in the system remained constant, the molecular weight distribution of the polymer chains was narrow, and SiO2-g-PMMA-b-PS was successfully prepared, which indicated that the polymerization conformed the characteristics of “living /controllable” polymerization. Finally, SiO2-g-PMMA particles were cured on the fabric surface in the form of layers, the water droplets did not infiltrate on the modified layer, and the contact angle was 166.2°, showing excellent superhydrophobic properties. Moreover, the modified layer performed well in the self-cleaning experiment and oil-water separation experiment.

AROMA: Anionic ring-opening monomer addition of allyl glycidyl ether to methoxy poly(ethylene glycol) for the synthesis of sequence-controlled polymers

Abstract Herein, a new method to synthesise epoxide-based sequence-controlled polymers via anionic ring-opening monomer addition, a form of anionic ring-opening polymerisation, is presented. This technique allows in combination with post-polymerisation modification (PPM) reactions for the successful preparation of modified mPEG-b-oligo(allyl glycidyl ether) featuring the incorporation of one repeating unit on average at a time. Due to the possible introduction of a vast variety of molecules to the polymeric system via PPM reactions, a multitude of advanced functional polymeric materials can be generated. This, in combination with the chain extension reactions, allows for the synthesis of well-controlled and programmable architectures with particular properties. The structure of the sequence-controlled polymer was confirmed via 1H NMR spectroscopy, size exclusion chromatography, attenuated total reflection Fourier-transform infrared spectroscopy, and differential scanning calorimetry.

Metal‐Free Atom Transfer Radical Polymerization of PVDF‐Based Block Copolymers Catalyzed by Organic Photoredox Catalysts

AbstractPoly(vinylidene fluoride) (PVDF) and its copolymers represent a class of electroactive fluoropolymers with very attractive piezo/ferroelectric properties that can be chemically modified to achieve high‐quality composites with improved properties. Here, the synthesis of poly(methyl methacrylate)‐b‐poly(vinylidene fluoride)‐b‐poly(methyl methacrylate) (PMMA‐b‐PVDF‐b‐PMMA) triblock copolymers via metal‐free light‐catalyzed atom transfer radical polymerization (ATRP) using organic photoredox catalysts (OPRC) and light of suitable wavelength is reported. Using benzoyl peroxide bearing an ATRP active group at both ends of the molecule, telechelic PVDF is synthesized, and is used as a macroinitiator in the metal‐free, light‐catalyzed ATRP in presence of methyl methacrylate (MMA), an OPRC, and light of suitable wavelength. Kinetic studies are performed by monitoring the monomer consumed in solution and by using 1H‐NMR to calculate the formation of the new PMMA blocks. Three of the five tested OPRC, operating through an oxidative quenching pathway, guarantee a good control over the polymerization, confirmed by the constant concentration of radicals during the process and by the linear growth of the conversion versus the percentage of monomer consumed. Chain extension reactions are also performed to prove chain‐end fidelity, as well as “light ON/light OFF” reactions to test the temporal control guaranteed by the external stimuli used to catalyze the polymerization.

Biobased Poly(ethylene succinate)-b-poly(triethylene terephthalate) multiblock copolyesters with high melting temperature and improved crystallization rate and mechanical property

Biobased poly(ethylene succinate)- b -poly(triethylene terephthalate) (PES -b- PTEGT) multiblock copolyesters with low weight ratios of PTEGT segment were successfully synthesized from dihydroxyl terminated PES and dihydroxyl terminated PTEGT prepolymers in this work through a chain extension reaction. The thermal, crystallization, and mechanical properties of PES -b- PTEGT were systematically investigated and compared with those of PES also prepared via the chain extension method. Two glass transition temperature ( T g ) values were detected for PES -b- PTEGT, corresponding to the T g of PES segment and that of PTEGT segment, respectively. PES -b- PTEGT showed a high melting temperature of around 100 °C and a thermal decomposition temperature of above 320 °C. The crystallizability of PES segment in PES -b- PTEGT was obviously enhanced under different crystallization conditions, which was attributed to the interface-assisted crystallization. In addition, the mechanical property (including both the elongation at break and the tensile strength) of PES -b- PTEGT was also remarkably improved. The synthesis of PES -b- PTEGT with a high melting temperature, faster crystallization rate, and improved mechanical property provided a new modification method to improve the physical property and extend the practical application of biodegradable polyesters. • Biobased PES -b- PTEGT copolyesters were synthesized via a chain extension reaction. • PES -b- PTEGT showed a high T m of around 100 °C and a T d of above 320 °C. • The crystallizability of PES segment in PES -b- PTEGT was obviously enhanced. • The mechanical property of PES -b- PTEGT was also remarkably improved. • This research proposed a novel method to modify the physical properties of PES.

Self-healing unsaturated polyester sensor based on multiple hydrogen bonds

Intelligent bio-based self-healing polymers are advanced and sustainable materials that are widely used in military, coatings and conductive materials. However, it is a challenging task to design unsaturated polyester materials with good stretching ability, efficient self-repair ability and sensitive sensing ability. In this paper, a class of bio-based unsaturated polyester is synthesized, and the functional self-repairing unsaturated polyester material is obtained through the control and design of its structure. Firstly, a flexible self-healing polyester crosslinking network (CPUBT-UPy) was prepared by introducing 2-urea-4[1H] pyrimidinone (UPy) into the unsaturated polyester chain through chain extension reaction and using polyethylene glycol (PEG) to regulate the structure and properties of unsaturated polyester. By adjusting the molar ratio of BDO and UPy, the elongation at break of the elastomer can reach 2020.94%, and the self-repair efficiency can reach 91.33%. After 5 repair cycles, the self-repair efficiency can still reach 79.01%. A flexible conductive material was prepared by the composite of CPUBT-UPy and 15% MWCNTs-NH2, and is further assembled into a universal flexible strain sensor, which showed excellent sensitivity to finger bending, speech and frowning. Finally, unsaturated polyesters also confer potential degradability on elastomers.

Preparation and Characteristic of Polyurethane Powder Adhesives with Heating Resistance Modified by Nanosilica

Polyurethane powder adhesives (PPAs) have a great application prospect in various areas. However, the weakly adhesion property at high temperature greatly hindered its application. In this study, nanosilica as reinforcing agent and dispersing agent has been introduced during the preparation of PPAs. A series of the polyurethane powder adhesives modified by nanosilica were prepared and the influence of adding order of nanosilica on the heat resistance and adhesive strength properties of PPAs has been investigated. The results showed that the T-peel strength of most samples after second heat (heated at 70°C for 24 hours) decreased about 60-80% comparing with the original T-peel strength. However, PPSY only decreased 17.5%, which indicated the nanosilica added after the chain extension reaction, in the prepolymer synthesis could increase the heat resistance performance of polyurethane powder adhesives. It also means the nanosilica was doped between the PU chains keeping the original form as enhancement reagent adding the nanosilica after the chain extension reaction. The excellent heat resistance performance of PPSY could meet the requirements of the industrial gluing in the fields of footwear.

High Mechanical Properties of Stretching Oriented Poly(butylene succinate) with Two-Step Chain Extension.

The structure, morphology, fracture toughness and flaw sensitivity length scale of chain-extended poly(butylene succinate) with various pre-stretch ratios were studied. PBS modification adopted from a multifunctional, commercially available chain-extension containing nine epoxy groups (ADR9) as the first step chain extension and hydroxyl addition modified dioxazoline (BOZ) as the second step. Time-temperature superposition (TTS) studies show that the viscosity increased sharply and the degree of molecular branching increased. Fourier transform infrared spectroscopy (FT-IR) confirm successful chain extension reactions. The orientation of the polymer in the pre-stretch state is such that spherulites deformation along the stretching direction was observed by polarized light optical microscopy (PLOM). The fracture toughness of sample (λfix = 5) is Γ ≈ 106 J m-2 and its critical flaw sensitivity length scale is Γ/Wc ≈ 0.01 m, approximately 5 times higher than PBS without chain-extension (Γ ≈ 2 × 105 J m-2 and Γ/Wc ≈ 0.002 m, respectively). The notch sensitivity of chain-extended PBS is significantly reduced, which is due to the orientation of spherulites more effectively preventing crack propagation. The principle can be generalized to other high toughness material systems.

Polydopamine Nanoparticle-Reinforced Near-Infrared Light-Triggered Shape Memory Polycaprolactone-Polydopamine Polyurethane for Biomedical Implant Applications.

Near-infrared (NIR) light-triggered shape memory polymers are expected to have a more promising prospect in biomedical applications compared with traditional heat-triggered shape memory polymers. In this work, a new kind of polyurethane with NIR light-triggered shape memory property was prepared by using polycaprolactone (PCL), polydopamine nanoparticles (PDANPs), hexamethylene diisocyanate (HDI), and 1,4-butanediol (BDO). The synthesized PCL-PDA polyurethanes, especially when the weight content of PDANPs was 0.17%, showed excellent mechanical properties because the PDANPs were well-dispersed in polyurethanes by the chain extension reaction. Moreover, it also showed an NIR light-triggered rapid shape recovery because of the photothermal effect of polydopamine. The in vitro and in vivo tests showed that the PCL-PDA polyurethane would not inhibit cell proliferation nor induce a strong host inflammatory response, revealing the non-cytotoxicity and good biocompatibility of the material. In addition, the PCL-PDA polyurethane exhibited excellent in vivo NIR light-triggered shape memory performance under an 808 nm laser with low intensity (0.33 W cm-2), which was harmless to the human skin. These results demonstrated the potential of the PCL-PDA polyurethane in biomedical implant applications.

Effect of hydroxyl and carboxyl-functionalized carbon nanotubes on phase morphology, mechanical and dielectric properties of poly(lactide)/poly(butylene adipate-co-terephthalate) composites

A series of poly(lactide)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) composites containing different types of multi-walled carbon nanotubes (CNTs) such as hydroxyl and carboxyl-functionalized CNTs were fabricated using the melt blending method. The multifunctional epoxy oligomer (ADR) was selected as a chain extender in order to enhance the compatibility between PBAT and PLA. It was revealed that the addition of ADR could induce CNTs-OH to locate at the PLA/PBAT interface. But the inhibition effect of CNTs-COOH on chain extension reaction in PLA/PBAT blend system led to a decrease in the interaction force between PLA and PBAT owing to the high efficiency of the reaction between CNTs-COOH and ADR. The ε’ of PLA/PBAT/4CNTs-OH composite was greater than that of PLA/PBAT/4CNTs-COOH composite because of the strong interaction between fillers and polymer matrix in PLA/PBAT/4CNTs-OH composite. The PLA/PBAT/4CNTs-OH composite showed a high ε’ (24.9) and a low tan δ (0.23), respectively. The adjacent CNTs-OH could act as assemble microcapacitors electrodes and the polymer acted as a dielectric to, which greatly increased the interfacial polarization. The PLA/PBAT/4CNTs-OH composite has excellent mechanical and dielectric properties.

Investigation on thermal degradation mechanism of poly(phenylene sulfide)

Thermal degradation occurs inevitably during the practical processing of poly(phenylene sulfide) (PPS) due to its low thermal stability, leading to the deterioration of processability and performance of PPS products. In this study, the structural evolution of PPS during thermal degradation in nitrogen (N2) and oxygen (O2) atmospheres are investigated systematically via X-ray photoelectron spectra (XPS), fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC) and dynamic rheology. A rheological measurement is proposed to distinguish the multi-stage degradation behaviors of PPS efficiently. It is found that the thermal degradation mechanism of PPS differs considerably in N2 and O2 atmospheres. Chain scission is predominant when PPS is heated in N2, while CS and CC crosslinking structures can only be initiated at extremely high temperature. On the contrary, oxidation of PPS is accelerated seriously in the presence of O2. Chain extension and branching reactions are activated even at low processing temperature of PPS, and substantial COC crosslinking structures are created which leads to the sharp increase of melt viscosity. Furthermore, the change of crystallization behaviors after thermal treatments of PPS are also studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The crystalline kinetics of PPS changes significantly during melt processing, which further corroborates the thermal degradation mechanism of PPS.

Modification of polylactide by reactive blending with polyhydroxybutyrate oligomers formed by thermal recycling through E1cB-elimination pathway

This study aimed to thermally recycle polyhydroxybutyrate (PHB), a microbial polyester with low thermal stability and limited re-processability, into crotonate-ended oligomers through the E1cB-elimination pathway. The resulting products were used as a functional additive to improve the mechanical and rheological properties of polylactide (PLA), which has intrinsic brittleness and low melt stability. The PLA was modified through a reactive blending process in an internal mixer. The quantitative 1H NMR analysis confirmed the crotonate functionality of the oligomers and their consumption during the reactive blending process. Tensile testing revealed that reactive blending 20 wt% PHB oligomers with PLA improve tensile toughness 24 times over pure PLA while keeping the elastic modulus above 1 GPa. Oscillatory-shear rheometry confirmed the improved shear-thinning behavior of reactive blends, while extensional viscosity measurements revealed a significant strain hardening behavior. The increase in melt stability was attributed to the formation of high molecular weight structures as a result of possible chain extension and branching reactions. DSC traces showed that branching and grafting points acted as nucleation sites, accelerating PLA melt crystallization. It was also found that increasing the PLA crystallinity above 44% gives rise to crystallization-induced phase separation, despite initial miscibility.

The tough, fluorescent and adhesive elastomer in aqueous dispersion: The contribution of aromatic amide-urea segments

The recent researches on waterborne polyurethane (WPU) have been much highlighted to fulfill the both requirements of environment and material performance. Herein, a simple copolymerization approach is demonstrated toward the tough, fluorescent and adhesive WPU elastomer films by the incorporation of para aromatic amide (aramid)-urea segments in the backbone of the polymer. The synthesis of the poly(amide-urea-urethane) was carried out through two steps of chain extension reactions, and the aramid motif, 4,4'-diaminobenzanilide (DABA) was used as the chain extender in the second step of chain extension before the polymer was neutralized and dispersed in water. The aramid-urea segments promoted the H-bonding association of the polyurethane matrix during the film formation of the WPU, which facilitated the microphase separation as well as the pronounced elevation of film performance. Under the DABA content of 4 wt%, the ultimate tensile strength increased to 73 MPa, 380% of that without DABA incorporation. Importantly, the WPU film showed remarkable toughness of 372 MJ·m-3 with the elongation at break of ~1250%. The water adsorption of the film was also suppressed to below 3% in 24 h of the water uptake test. Not only that, but the elastomer film also exhibited high adhesion to metal surfaces to withstand a hanging weight of 27.5 kg with the bonding area of 25 mm × 50 mm. Besides, the film was also able to emit bright blue fluorescence under the excitation of UV light. The combining of high strength, toughness, water resistance and photoluminescence in the WPU will provide the elastomer great potential as environmentally friendly multifunctional material.

Preparation of Emulsifier-Free Styrene-Acrylic Emulsion via Reverse Iodine Transfer Polymerization.

Styrene–acrylic emulsions containing hydroxyl functional monomer unit’s component are widely used for maintenance coating. In this paper, a stable emulsifier-free styrene–acrylic emulsion with solid content over 43% could be obtained in 210 min via reverse iodine transfer polymerization (RITP). By adding a mixture of methacrylic acid (MAA) and poly(ethylene glycol)methyl ether methacrylate (PEGMA) into a system containing a high content of hydroxyl functional monomer component (19.4 wt.% of the total monomer mass), styrene (St) could be copolymerized with methyl methacrylate (MMA); the modified film exhibited good hardness properties, good adhesive properties, and low water absorption. An increase in the amount of PEGMA decreased the glass transition temperature (Tg). When 1.4 times the reference amount of initiator was added, the highest molecular weight Mn could reach 40,000 g.·mol−1 with 0.25 times the reference amount of iodine in the emulsion. The largest tensile strength of the dried emulsion film over 5.5 MPa endowed the material with good mechanical properties. Living polymerization was proven by the kinetics of RITP emulsion and chain extension reaction. TEM micrographs manifest the emulsification of the seed random copolymer. This paper may provide a potential methodology for preparing polymer materials with excellent mechanical properties.

Preparation and properties of aniline chain‐extended thermoplastic epoxy resin using triphenylphosphine as catalyst

Thermoplastic resins have been widely used in fiber reinforced polymer composites because of its recyclability and short cycle times. However, the high viscosity after heating and melting restricts its infiltration on the surface of fiber. In this study, a series of thermoplastic epoxy resins were prepared via the chain extension reaction of epoxy groups with liquid aniline using triphenylphosphine (TPP) as catalyst. The relationship between polymer network structure and performance was comprehensively investigated. The solubility tests indicated that excessive aniline or TPP facilitated the crosslinking of resins. Besides, on the premise of thermoplasticity, appropriate TPP could increase the degree of chain extension, molecular weight, and glass transition temperature of resins. Furthermore, the in‐situ polymerization process facilitated infiltration between epoxy resin and the fibers before chain extension reaction. The bending test showed that the flexural performance of the sample with 2 phr of TPP was improved by 38.8%. Therefore, this work provides a feasible method to prepare the thermoplastic epoxy resins and its fiber‐reinforced composites with good mechanical properties.

Visible Light-Regulated Heterogeneous Catalytic PET-RAFT by High Crystallinity Covalent Organic Framework.

Covalent organic frameworks (COFs) are a class of promising photocatalysts for conversing light energy into chemical energy. Based on the tunable building blocks, COFs can be well-designed as photocatalyst for mediating reversible addition-fragmentation chain-transfer (RAFT) polymerization. Herein, 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) and 2,2″-bipyridine-5,5″-diamine (Bpy) are chosen to construct imine-based TFPPy-Bpy-COFs for catalyzing RAFT polymerization of methacrylates under white light irradiation. The well-defined polymers with precise molecular weight and narrow molecular weight distribution are obtained. The switch on/off light experiments suggest excellent temporal control toward RAFT polymerization system and the chain-extension reaction indicates high chain-end fidelity of macro-initiators. Mechanism study clarifies that the electron transfer between excited state of TFPPy-Bpy-COFs and RAFT agent can form living radicals to mediate polymerization. This methodology provides a novel platform for reversible-deactivation radical polymerization using COFs as heterogeneous catalysts.

Reversible Chain Transfer Catalyzed Polymerization with Alkyl Iodides Generated from Alkyl Bromides by in Situ Halogen Exchange

Reversible chain transfer catalyzed polymerization (RTCP) is a practical and efficient process for the precise synthesis of polymers with special architecture by using simple phenols (2,4,6-trimethylphenol, TMP) or hydrocarbons (xanthene, XT) as efficient organocatalysts. Herein, alkyl iodide (R-I) which was generated from in situ bromine-iodine transformation of alkyl bromide (R-Br) with sodium iodide (NaI), was served as initiator to mediate RTCP with TMP or XT. MMA and other functional methacrylates, including GMA, DEAM, DMAEMA and BzMA, were successfully initiated by combining organocatalysts and azo initiators to yield polymers with low-polydispersity (Mw/Mn=1.1-1.5) and ideal monomer conversions (50-90%) at moderate temperature. Moreover, 3-arm star polymers were also obtained by this method. The high chain-end fidelity of the obtained poly(methyl methacrylate) with iodine as chain-end group (PMMA-I)was confirmed by chain-extension reaction. The environmentally friendly initiators and organocatalysts exhibit powerful polymerization properties toward RTCP, providing a significant method to synthesize functional polymers.

Synthesis, characterization and dispersion stabilities of novel ionic and nonionic diol modified waterborne polyurethane dispersions with different polyols

Several high solid content waterborne polyurethane dispersions (WPUDs) with the combination of anionic and nonionic stabilization were synthesized by polyaddition reaction using isophorone diisocyanate (IPDI), trimethylol propane (TMP) and 1,6-hexanediol (HDO) as the hard segments, polypropylene glycol with molecular weight of 2000 Da (PPG-2000), and polytetramethylene ether glycol with molecular weight of 2000 Da (PTMG-2000) as the soft segments, anionic diol dimethylol propionic acid (DMPA) and nonionic diol Y-mer N 120 (NID) as the donors of hydrophilic groups. The chain extension reaction between residual NCO groups was made by using hydrazine (HYD). The effects of the combination of anionic and nonionic monomer and macrodiol types on the performance of the WPUDs were studied in terms of particle size distribution and dispersion stability. The results showed that the WPUDs exhibited narrow particle size distribution, good appearance and good mechanical properties.

A facile approach to realize simultaneously chain extension and crystallization promotion of poly (ethylene terephthalate)

A synergic strategy combining chemical nucleation with chain extension was employed for Poly (ethylene terephthalate) (PET). In this study, sodium linoleate (Na-LL), as chemical nucleating agent, was selected to promote the nucleation process, and an ultraviolet-induced chain extension approach was simultaneously employed to maintain the molecular weight of PET with the aid of glycidyl methacrylate (GMA) / trimethylolpropane triacrylate (TMPTA). The rheological properties, crystallization behaviors and mechanical properties of PET composites were systematically explored. The rheological results showed that GMA/TMPTA blend is effective for PET chain extension reaction and the addition of Na-LL would not badly offset the chain extension effect of GMA/TMPTA. The non-isothermal and isothermal crystallization studies demonstrated that Na-LL is an effective organic nucleating agent for PET. Low loading of Na-LL can considerably improve the crystallization properties of PET. At last, the combination of GMA/TMPTA/Na-LL could also maintain the excellent comprehensive mechanical properties of PET.